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原文传递 Minimizing Water Quality Impacts of Road Construction Projects.

题名：	Minimizing Water Quality Impacts of Road Construction Projects.
作者：	mclaughlin, r. a. jennings, g. d.
关键词：	road construction projects,water quality impacts,polyacrylamide (pam)/impact reduction evaluation, ground covers, sediment capture, polyacrylamide, erosion/
摘要：	This study was initiated to determine the potential impacts of sediment from a large construction project on nearby streams, and to evaluate approaches to reduce those impacts. There were three main aspects of the project, which was located at the construction of Interstate 485 on the northwest side of Charlotte: evaluate ground covers, test and evaluate sediment capture using different designs, and quantify the current conditions of a stream that parallels the project. The clearest improvements over the standard straw + tackifier occurred as the result of adding polyacrylamide (PAM), which usually reduced erosion considerably. There was no obvious advantage of PAM in establishing vegetation, however. Among the alternative ground covers, the results were inconclusive due to high variability. The bonded fiber matrix product appeared to have the lowest erosion rate but excelsior was also usually low. The vegetation may have been favored by excelsior compared to the other covers, but the differences were not large. A system of ditch lining and frequent check dams, stabilized basin inlets, porous baffles, and skimmer/spillway outlets clearly reduced the magnitude of sediment loss from disturbed areas. Turbidity reduction by PAM was evident during low flow events or portions of events. Methods for dosing higher flow events with PAM need to be investigated as a method to reduce turbidity, which usually cannot be removed economically any other way. The structures installed to divert water and remove sediment often generate significant amounts of sediment. Unlined, deep perimeter ditches were a major source, and sediment traps with vertical walls and unprotected inlets also were sources. Large disturbances in a watershed will impact water quality using current systems for erosion and sediment control. There was no evidence that the aquatic biology of Long Creek changed over the four years of various levels of disturbance. However, it was in poor to fair condition biologically when we initially sampled in 2003. There was no evidence of increased bank erosion during the period 2003-2006 when we surveyed Long Creek. These surveys were intended primarily as baseline information for surveys 5-10 years from now, when the watershed becomes even more densely developed. / NOTE: Final rept. (Sept. 2002 - Aug. 2006). / Supplementary Notes: Sponsored by North Carolina Dept. of Transportation, Raleigh. and Federal Highway Administration, Raleigh, NC. North Carolina Div. / Availability Note: Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at orders@ntis.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA.
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